NASA – Hubble Detects Evaporating Planet

Artist's concept of the evaporating planet (ESA/NASA)

New Worlds Atlas

Space Telescope Science Institute press release European Space Agency press release

(PLANET QUEST) -- The atmosphere surrounding a planet slightly larger than Jupiter is apparently being seared into space from the intense heat of its parent star, astronomers said in early March.

Astronomers used the Hubble Space Telescope to observe the evaporating atmosphere of the planet, which is one of about 105 gas giants that have been discovered thus far outside our solar system. The planet is located some 4 million miles (7 million kilometers) from its yellow star -- a much closer proximity than that of any planet to our own Sun.

The Hubble observations reveal a hot and bloated hydrogen atmosphere, which is evaporating off the planet. The huge envelope of hydrogen resembles a comet with a tail trailing behind the planet.

Astronomers estimate the amount of hydrogen gas escaping the planet, named HD 209458 b, to be at least 10,000 tons per second, but possibly much more. Much of the planet may eventually disappear, leaving only a dense core.

An international team of astronomers, led by Alfred Vidal-Madjar of the Institut d'Astrophysique de Paris, CNRS, France, is reporting the discovery in the March 13 Nature Magazine.